1. Field of the Invention
The present invention relates to a method and apparatus for generating and accessing metadata in a media file format, and more particularly, to a method and apparatus for generating and accessing a metadata structure suitable for real-time reproduction and modification of a multimedia object in a media file format.
2. Description of the Related Art
As the manufacture and use of multimedia content increases, a need to search for and filter multimedia content has emerged, and various methods for encoding metadata have been suggested.
Metadata refers to data that briefly describes the contents and characteristics of information in a specific format in order to make the information easy to search for and easy to access information resources in various formats, i.e., information about the information resources.
FIG. 1 illustrates a general metadata structure in a media file format.
Referring to FIG. 1, the media file format is composed of media objects divided on a track basis. The media object means an object that constitutes content as an audio frame, a video frame, or an image frame. The track means a channel through which the media object continuously flows.
A media file 110 is divided into several tracks, and an object called a sample table 130 is linked to a track header 120 of each of the tracks. The sample tables 130 include time (offset time) information 140 during which linked media objects 160 are executed and position (offset position) information 150 of the media objects 160.
The media objects 160 are linked using the position information 150 included in the sample tables 130 and are accessed and reproduced based on the time information 140 included in the sample tables 130.
Since the general metadata structure has a static track structure, a user has to sequentially access all track headers and all sample tables even if the user desires to access only particular unit time, e.g., a time interval between 5 minutes and 6 minutes after the start of content execution in a particular track, e.g., a track #3.
Moreover, in order to update media file data, e.g., to delete track #1 and track #2, the sample tables 130 have to be moved, e.g., tracks #3 to #N have to be moved to tracks #1 to #N−2. Furthermore, the position information 150 included in the sample tables 130 has to also be changed in order to change the positions of media objects as well as to update the media file data.